Submission #924626

#	Time	Username	Problem	Language	Result	Execution time	Memory
924626		esomer	Maze (JOI23_ho_t3)	C++17	100 / 100	1881 ms	160984 KiB

Main

#include <bits/stdc++.h>
 
using namespace std;
 
int dirI[] = {0, 0, 1, -1};
int dirJ[] = {1, -1, 0, 0};
 
int R, C, N;
 
bool isBest(int d1, int d2, pair<int, int>& p){
	int mn1, mx1, mn2, mx2;
	if(d1 < d2){
		mn1 = d1;
		mx1 = d2;
	}else{
		mn1 = d2;
		mx1 = d1;
	}
	if(p.first<p.second){
		mn2 = p.first;
		mx2 = p.second;
	}else{
		mn2 = p.second;
		mx2 = p.first;
	}
	if(!((mx1 <= N && mn1 < N) || (mx2 <= N && mn2 < N))) return false;
	if(mx1 == mx2) return mn1 < mn2;
	else return mx1 < mx2;
}
 
int main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
 
	cin >> R >> C >> N;
	int Sr, Sc, Gr, Gc; cin >> Sr >> Sc >> Gr >> Gc; Sr--; Sc--; Gr--; Gc--;
	vector<string> v(R);
	for(auto &i : v) cin >> i;
	vector<pair<int, int>> added = {{Sr, Sc}};
	vector<vector<int>> dist(R, vector<int>(C, 1e9));
	vector<vector<bool>> vis(R, vector<bool>(C, false));
	vector<vector<pair<int, int>>> best(R, vector<pair<int, int>>(C, {1e9, 1e9}));
	dist[Sr][Sc] = 0;
	for(int t = 0; t < 2*R*C; t++){
		if(t==0){
			//Time to freely expand;
			queue<pair<int, int>> q;
			for(pair<int, int>& p : added){
				q.push(p);
			}
			while(!q.empty()){
				int i = q.front().first; int j = q.front().second; q.pop();
				if(i == Gr && j == Gc){
					cout << dist[i][j] << "\n";
					return 0;
				}
				// cout << "i " << i+1 << " j " << j+1 << " dist " << dist[i][j] << "\n";
				for(int k = 0; k < 4; k++){
					int ai = dirI[k]; int aj = dirJ[k];
					if(i + ai < 0 || i + ai >= R || j + aj < 0 || j + aj >= C) continue;
					int ni = i + ai; int nj = j + aj;
					// cout << "ni " << ni << " nj " << nj << "\n";
					if(v[ni][nj] == '.' && dist[ni][nj] > dist[i][j]){
						dist[ni][nj] = dist[i][j];
						added.push_back({ni, nj});
						q.push({ni, nj});
					}
				}
			}
		}else{
			priority_queue<pair<int, int>> q;
			int d = 0;
			for(pair<int, int>& p : added){
				q.push({0, p.first*C+p.second});
				best[p.first][p.second] = {0, 0};
				d = dist[p.first][p.second];
				vis[p.first][p.second] = false;
			}
			added.clear();
			while(!q.empty()){
				int val = q.top().second; q.pop();
				int i = val/C; int j = val%C;
				if(i == Gr && j == Gc){
					cout << dist[i][j] << "\n";
					return 0;
				}
				if(vis[i][j]) continue;
				vis[i][j] = true;
				if(best[i][j].first >= N || best[i][j].second >= N){
					added.push_back({i, j});
				}
				for(int k = 0; k < 4; k++){
					int ai = dirI[k]; int aj = dirJ[k];
					if(i + ai < 0 || i + ai >= R || j + aj < 0 || j + aj >= C) continue;
					int ni = i + ai; int nj = j + aj;
					if(dist[ni][nj] > d && isBest(best[i][j].first+abs(ai), best[i][j].second+abs(aj), best[ni][nj])){
						dist[ni][nj] = d+1;
						best[ni][nj] = {best[i][j].first+abs(ai), best[i][j].second+abs(aj)};
						q.push({-max(best[ni][nj].first, best[ni][nj].second)*(N+2)+min(best[ni][nj].first, best[ni][nj].second), ni*C+ nj});
					}else if(dist[ni][nj] > d + 1 && v[ni][nj] == '.'){
						dist[ni][nj] = d + 1;
						q.push({2e9, ni*C+ nj});
					}
				}
			}
		}
	}
	cout << dist[Gr][Gc] << "\n";
}

• Subtask 1: 8 / 8
• Subtask 2: 19 / 19
• Subtask 3: 16 / 16
• Subtask 4: 19 / 19
• Subtask 5: 5 / 5
• Subtask 6: 19 / 19
• Subtask 7: 8 / 8
• Subtask 8: 6 / 6